1. Field of the Invention
The present invention relates to a film forming method comprising: moving a substrate and nozzle with respect to each other; dropping solution onto the substrate from a solution discharge nozzle; and forming a liquid film of the solution on the substrate.
2. Description of the Related Art
To use a spin coating method in a lithography process and interlayer film formation, most of the solution dropped onto a substrate is discharged off the substrate, and a film is formed with the remaining several percent of the solution. Therefore, there is much waste, and the environment is adversely affected. Moreover, there has been a problem that turbulence is generated in an outer peripheral portion of a square substrate or a circular substrate having a large diameter of 12 inches or more, making the film thickness nonuniform in that portion.
As a method of uniformly coating the whole surface of the substrate without wasting in Jpn. Pat. Appln. KOKAI Publication No. 2-220428, a method is described which comprises: dropping resist from a large number of nozzles arranged in one row; and spraying a gas or solution onto a film forming surface from behind the nozzles to obtain a uniform film. Further, in Jpn. Pat. Appln. KOKAI Publication No. 6-151295, a large number of spray ports are disposed in a bar; and the resist is dropped onto the substrate from the ports to obtain a uniform film. Furthermore, in Jpn. Pat. Appln. KOKAI Publication No. 7-321001, a method is described comprising: using a spray head in which a large number of jet holes are formed to spray the resist; and moving the head with respect to the substrate to coat the substrate. In all of these coating apparatuses, a plurality of dropping or spray nozzles are transversely arranged in a row, so as to scan the nozzles along the substrate surface and a the uniform film. In addition to these coating methods, there is a method using one solution discharge nozzle, and scanning the nozzle to form a liquid film. This method has a problem that the treatment time per substrate depends on the operation method of the nozzles, and the amount of solution used becomes enormous.
As an apparatus for solving the problem, in Jpn. Pat. Appln. KOKAI Publication No. 9-92134, a method is disclosed which comprises: reciprocating/moving the solution discharge nozzle over the substrate to drop the solution onto the substrate. The method further comprises: stopping liquid supply in each terminal end of the reciprocating/moving on the substrate; and re-supplying the solution in a start point to form the coating film. However, the solution amount supplied onto the substrate slightly differs due to uneven liquid supply caused by stoppage and restart of liquid supply at the terminal end and start point, and a problem has occurred that film thickness uniformities of the liquid film and solid film formed from the liquid film are deteriorated.
On the other hand, in Jpn. Pat. Appln. KOKAI Publication Nos. 2000-77307, 2000-77326, 2000-79366, 2000-188251, 2001-148338, 2001-168021, 2001-170546, 2001-176781, 2001-176786, 2001-232250, and 2001-232269, a method is disclosed comprising: maintaining the discharge of the solution even in a turn-back portion in the reciprocating movement of the solution discharge nozzle; and supplying a coating film in which a film thickness distribution at an edge vicinity (the vicinity of turn-back of reciprocating movement) is not deteriorated. However, in the coating apparatus described in these publications, a distance between the solution discharge nozzle and substrate is not considered. Depending on the discharge speed from the solution discharge nozzle, surface tension of the solution, and distance between the solution discharge nozzle and substrate, in a process of spread of liquid flow before the solution reaches the substrate, liquid drops are produced by the surface tension of the liquid, and the liquid drops which have reached the substrate are sputtered, causing a problem of mist or vapor.
Moreover, in the above-described forming method in the liquid film, in each region of the substrate surface to be treated, because of differences of physical properties, discharge pressure of the nozzle, further variations in discharge amount of the solution, or turbulence of air currents at the coating time, the film thickness of the liquid film does not become uniform, and sometimes varies over the whole surface of the substrate. When a solvent in the liquid film is vaporized in this state, a film of a solid content (=solid film) is formed on the substrate with low flatness in accordance with the film thickness distribution of the liquid film.
Moreover, even when the liquid film is formed in a excellent flatness state, when a drying process is thereafter executed so as to vaporize the solvent, aggregation occurs toward the middle portion of the substrate. In this manner, the solid content moves with the movement of the liquid film in a transverse direction, and a difference in film thickness is generated in the movement direction.
When a such photo resist film which is formed using the such method is subjected to exposure and development processes to form a pattern, a critical dimension (CD) error is generated in the pattern. In a process in which this pattern is used as a mask to subject a lower layer film (e.g.: insulating film, and conductive wiring film) to etching processing, the CD error is further enlarged. This was an effect of reducing the yield.
As disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2001-237179, with respect to the variation in thickness of the liquid film, there has heretofore been a method comprising: forming the liquid film; subsequently exposing the film to a solvent vapor to promote fluidity of the solution; and performing a so-called leveling treatment so that the surface of the liquid film is flatted by the surface tension.
However, in the prior-art leveling treatment, the solvent is unnecessarily supplied to the surface of the liquid film, and the film thickness is uneven. Inclination is generated in the film thickness of the liquid film (e.g., peripheral edge) by an inadequate condition.
Additionally, a manufacturing process of the semiconductor apparatus comprises: coating the substrate surface with a resist solution in which resist materials such as a resin, dissolution inhibitor (dissolution inhibitor group), and acid generating material (acid generation group) are dissolved in organic solvent (ethyl lactate, etc.) to form the liquid film; and subsequently evaporating the solvent in the liquid film to form the resist film. The resist film formed on the substrate is exposed to light, then bake-treated, cooled, and developed to form a resist pattern.
Some of the resist patterns formed as described above have a problem that the upper part of the resist pattern is rounded. Since the upper surface of the resist film is exposed to a developing liquid for a long time, the upper part becomes rounded. To solve this problem, a layer containing many dissolution inhibitor can be formed in the surface layer.
However, to form the layer containing many dissolution inhibitor in the surface layer, a prior art method has to comprise: coating the substrate with a first resist solution film; baking and forming a first resist film; coating the first resist film with a second resist solution film using a resist solution which containing the dissolution inhibitor more than the resist solution used in forming the first resist film; and baking and forming the second resist film. In this method, two resist films have to be separately formed, which lengthens manufacturing time.
As a prior-art method of forming the coating film on the substrate, there is a method comprising: relatively moving a discharge nozzle which discharges a given amount of solution on the substrate; discharging the solution over the whole surface of the substrate to form a liquid film; and thereafter evaporating the solvent by an appropriate dry method to form the film. In this method, a solution which has a small solid content and has a low viscosity in a range of about 0.001 Paxc2x7s to 0.010 Paxc2x7s (1 cp to 10 cp) is used. When the liquid film is formed on a substrate having a stepped portion in this coating method, the formed liquid film is fluidized by gravity, and a concave/convex portion is smoothed. A difference is generated in the thickness of the finally prepared coated film, that is, the film thickness of the concave portion increases and that of the convex portion decreases. As a result, there is a problem that a film having a uniform thickness cannot be formed on the substrate surface.
(1) According to one aspect of the present invention, there is provided a film forming method of discharging a solution from a discharge port of a nozzle onto the substrate, and then providing relative movement between the nozzle and the substrate while keeping the liquid discharging on the substrate, so as to form a liquid film on the substrate,
wherein a distance h between the discharge port of the nozzle and the substrate is set to be not less than 2 mm and to be less than Aqxcex3 (mm),
wherein q (m/sec) denotes a discharge speed of the solution continuously discharged through the discharge port,
xcex3 (N/m) denotes a surface tension of the solution, and
A (mxc2x7sec/N) is 5xc3x9710xe2x88x925.
(2) According to another aspect of the present invention, there is provided a film forming method comprising:
registering a surface tension xcex3 (N/m) of a solution adjusted so as to spread over the substrate by a given amount;
calculating a distance h between a discharge port of a nozzle and a substrate, which is not less than 2 mm and is less than 5xc3x9710xe2x88x925 qxcex3 (mm), from a discharge speed q (m/sec) of the. solution continuously discharged to the substrate through the discharge port of the nozzle, surface tension xcex3 (N/m) of the solution, and constant of 5xc3x9710xe2x88x925 (mxc2x7sec/N); and discharging a solution from a discharge port of a nozzle onto the substrate, and then providing relative movement between the nozzle and the substrate while keeping the liquid discharging on the substrate.
(3) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement in a column direction in which a nozzle passes along a substrate from one end of the substrate to the other end of the substrate with a movement in a row direction inside or outside the substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the substrate by a given amount through a discharge port disposed in the nozzle; holding the discharged solution on the substrate; and forming a liquid film, further comprising:
obtaining a deviation amount of a discharge amount of the solution from a desired value with respect to a discharge position of the solution, when the solution is discharged onto the substrate from the nozzle moving in a first column; and
controlling the discharge amount in an arbitrary position in a second column so as to compensate for the deviation amount obtained in an adjacent discharge position on the first column, when the solution is discharged onto the substrate from the nozzle moving on a second column disposed adjacent to the first column.
(4) According to still another aspect of the present invention, there is provided a film forming method comprising: moving a nozzle in a diameter direction of a substrate over the substrate which rotates; continuously discharging a solution adjusted so as to spread over the substrate by a given amount through a discharge port disposed in the nozzle; and holding the supplied solution on the substrate to form a liquid film, further comprising:
obtaining a deviation amount of a supply amount of the solution from a desired value with respect to a discharge position of the solution, when the solution is supplied onto the substrate from the nozzle; and
controlling the supply amount of the solution discharged to a first position, so as to compensate for the deviation amount in a second position which is disposed adjacent to the first discharge position in the diameter direction of the substrate and to which the solution has already been discharged, during the supply of the solution into the first position of the substrate from the nozzle.
(5) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement in a column direction in which a nozzle passes along a substrate from one end of the substrate to the other end of the substrate with a movement in a row direction inside or outside the substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the substrate by a given amount through a discharge port disposed in the nozzle; holding the discharged solution on the substrate; and forming a liquid film, further comprising:
cutting off the solution discharged onto the substrate from the nozzle so that a supply start point and supply end point of the solution discharged onto the substrate from the nozzle reach a liquid film edge forming position apart from each edge of the substrate by a given width d during the movement of the nozzle in the column direction.
(6) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement of a column direction in which a nozzle passes along a circular substrate from one end of the circular substrate through the other end of the substrate with a movement of a row direction in the vicinity of an edge of the circular substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the circular substrate by a given amount to the substrate through a discharge port disposed in the nozzle; holding the discharged solution onto the substrate; and forming a liquid film over the whole surface of the substrate to an end position from a start position,
wherein a movement speed of the column direction of the nozzle in the vicinity of the start position is set to be lower than the movement speed of the column direction of the nozzle in a middle position of the substrate; and
the movement speed of the column direction of the nozzle in the vicinity of the end position is set to be higher than the movement speed of the column direction of the nozzle in the middle position of the substrate.
(7) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement of a column direction in which a nozzle passes along a circular substrate from one end of the circular substrate through the other end of the substrate with a movement of a row direction in the vicinity of an edge of the circular substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the circular substrate by a given amount to the substrate through a discharge port disposed in the nozzle; holding the discharged solution onto the substrate; and forming a liquid film over the whole surface of the substrate to an end position from a start position,
wherein a movement distance of the row direction of the nozzle in the vicinity of the start position is set to be longer than the movement distance of the row direction of the nozzle in a middle position of the circular substrate; and
the movement distance of the row direction of the nozzle in the vicinity of the end position is set to be shorter than the movement distance of the row direction of the nozzle in the middle position of the substrate.
(8) According to further aspect of the present invention, there is provided a film forming method comprising: combining a linear movement of a column direction in which a nozzle passes along a circular substrate from one end of the circular substrate through the other end of the substrate with a movement of a row direction in the vicinity of an edge of the circular substrate to move the nozzle and substrate with respect to each other; continuously discharging a solution adjusted so as to spread over the circular substrate by a given amount to the substrate through a discharge port disposed in the nozzle; holding the discharged solution onto the substrate; and forming a liquid film over the whole surface of the substrate to an end position from a start position,
wherein a time interval from when the solution supply to the substrate by the movement of the column direction of the nozzle including the movement of the row direction of the nozzle is temporarily discontinued until the solution supply to the substrate by the movement of the column direction of the nozzle is restarted is set to be constant.
(9) According to one aspect of the present invention, there is provided a film forming method comprising:
forming a liquid film constituted of a solution including a first solvent and solid content on a substrate;
containing the substrate in a container;
starting a leveling treatment to flat the surface of the liquid film in a state in which an atmosphere including a second solvent is formed in the container;
measuring flatness of the surface of the liquid film during the leveling treatment;
controlling at least one of the atmosphere in the container and temperature of the substrate based on the measured flatness during the leveling treatment to enhance the flatness of the surface of the liquid film;
ending the leveling treatment; and
forming a solid film including the solid content on the substrate.
(10) According to further aspect of the present invention, there is provided a film forming method comprising:
forming a liquid film including a solid content and solvent on a substrate;
starting a drying treatment to remove the solvent in the liquid film;
measuring flatness of the surface of the liquid film during the drying treatment;
controlling at least one of the atmosphere of environment in which the substrate exists, temperature of the substrate, and rotation speed of the substrate based on the measured flatness during the drying treatment to enhance the flatness; and
ending the drying treatment to form a solid film including the solid content on the substrate.
(11) According to one aspect of the present invention, there is provided a film forming apparatus comprising:
a support unit to support a substrate on the surface of which a liquid film including a first solvent is formed;
a container including the support unit disposed in an inner space;
a gas supply unit which includes a discharge port and which supplies gas including a second solvent into the container through the discharge port;
an exhaust unit which exhausts air from the atmosphere in the container;
an optical system which irradiates the liquid film on the substrate supported on the support unit with light, receives reflected light from the liquid film, and obtains reflected light intensity; and
an analysis unit which analyzes the reflected light intensity obtained by the optical system to measure flatness of the liquid film surface and which controls the exhaust unit and gas supply unit so as to enhance the measured flatness.
(12) According to another aspect of the present invention, there is provided a film forming method comprising:
forming a liquid film including a solution in which a first material is dissolved in a solvent on a substrate;
removing the solvent from the liquid film, until a substrate side of the liquid film solidifies and the solvent remains on a side opposite to the substrate side;
supplying a second material into the liquid film in a state in which the solvent remains in a surface layer of the liquid film; and
removing the solvent remaining in the liquid film to form a solid film.
(13) According to further aspect of the present invention, there is provided a film forming method comprising:
preparing a substrate which includes a concave/convex portion having a stepped portion height of d and in which a rate of an area of the convex portion to the whole area is a (1 greater than a greater than 0) and a rate of an area of the concave portion to the whole area is 1xe2x88x92a;
discharging a solution in which a solid content is dissolved in a solvent, moving a discharge nozzle and substrate with respect to each other, and forming a liquid film on the substrate; and
removing the solvent in the liquid film, and forming a solid film including the solid content, wherein the liquid film is formed so that a thickness h of the liquid film satisfies a relation of h greater than (11xe2x88x92a)d.